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4.2.2 pH Sampling <br />pH monitoring is required for "Significant concrete work" (i.e., greater than 1000 cubic yards <br />poured concrete over the life of the project). The use of recycled concrete or engineered soils <br />(soil amendments including but not limited to Portland cement -treated base [CTB], cement kiln <br />dust [CKD] or fly ash) also requires pH monitoring. <br />For significant concrete work, pH sampling will start the first day concrete is poured and <br />continue until it is cured, typically three (3) weeks after the last pour. <br />For engineered soils and recycled concrete, pH sampling begins when engineered soils or <br />recycled concrete are first exposed to precipitation and continues until the area is fully <br />stabilized. <br />If the measured pH is 8.5 or greater, the following measures will be taken: <br />1. Prevent high pH water from entering storm sewer systems or surface water. <br />2. Adjust or neutralize the high pH water to the range of 6.5 to 8.5 su using appropriate <br />technology such as carbon dioxide (COO sparging (liquid or dry ice). <br />3. Written approval will be obtained from Ecology prior to the use of chemical treatment <br />other than CO2 sparging or dry ice. <br />Method for sampling pH: <br />This project does not have any concentrated discharge. As a result, pH Sampling will not be <br />necessary. <br />Table 9 — pH Sampling Method <br />❑ <br />H meter <br />❑ <br />H test kit <br />❑ <br />I Wide range PH indicator paper <br />Page 126 <br />